The invention relates to an electromagnetic 3-way valve assembly which is intended to be placed at the junction of a pressure receiver, a source of pressure and a relief location and which is provided with an armature carrying the closure members of a dual seat valve. When the valve is not energized, a main spring presses the armature into an initial position whereas, when energized, the magnetic force urges it in the direction of a counter end member or pole piece. The armature includes two closure members which are somewhat movable with respect to one another and also with respect to the armature and which are urged apart by a single spreader spring also located in the armature. Each of the closure members is provided with a holding flange that is axially movable in an interior groove of the armature.
A 3-way valve assembly of this kind has already been proposed previously and in that valve assembly, the spring forces must be matched to the magnetic forces. In addition, both the magnetic as well as the spring forces are subject to a certain amount of variation in magnitude due to hysteresis. Changes in pressure, frictional forces and the effects of dimensional tolerances all contribute to a relatively broad spread in the magnitude of the forces acting on the armature. Furthermore, it is sometimes advantageous if the stroke of the valve is relatively long so as to provide a certain minimum cross section for the flow of the pressure medium.